An alternative key to adult Dytiscidae and Noteridae of Massachusetts, USA
Betsy A. Colburn, Harvard University, 324 North Main Street, Petersham, MA 01366
The identification of adult Noteridae and Dytiscidae is challenging for many experts, and more so for students, interns, and others with limited experience with beetles. It can be easy to go astray with the standard dichotomous keys, and to misidentify some specimens. This poster presents a new, generic-level key to adult noterids and dytiscids of Massachusetts. The key draws on a variety of existing identification sources, published descriptions of genera and species, and practical experience. Instead of strictly dichotomous choices, the key presents multiple criteria, all of which are met by several genera, and then specifies the distinguishing characteristics for each genus within the group. For example, Bidessonotus and Laccophilus share the combined features of “fore and middle tarsi with five readily-visible segments; scutellum covered; prosternal process pointed, spear-shaped; absence of a curved spur at apex of front tibia,” and are separated from each other by size, number of tarsal claws, and the presence or absence of plicae on pronotum and elytra. This simplified key, used in parallel with a modified dichotomous key that is also restricted to genera found in New England, has been useful in improving the accuracy of identification of adult dytiscids and noterids in our laboratory.